The synthesis of isoxazolic derivatives was thoroughly studied in the past and several methods for preparing the said compounds are known and described in the scientific literature [cf e.g.: Ber., 28,2540 (1895); idem 36,3665 (1903); Compt. Rend., 137,795 (1903); J. Am. Chem. Soc., 49, 2078 (1927); Gazz. Chim. Ital., 70,676 (1940); idem, 72,99 (1942); idem, 76,148 (1946)]. The methods described in the aforementioned references can be distinguished depending on whether they relate to syntheses achieved by
Swiss Pat. No. 553,207 discloses a process for the preparation of isoxazoles of formula ##STR7## possessing an endocyclic double bond in position 1, 2, 3 or 4, or an exocyclic double bond in position 2, or two conjugated double bonds in positions 1 and 3 as indicated by the dotted lines and wherein R.sup.1 and R.sup.2 represent a lower alkyl radical or a hydrogen atom, which process is characterized in that an alpha,beta-unsaturated oxime of formula ##STR8## is cyclized by means of a stoichiometric amount of iodine, preferably in a neutral or alkaline aqueous medium. In order to maintain the required iodine in solution in the aqueous medium, it was suggested to add to it potassium iodide, that needed to be used in large excess (3 or 4 equivalents). The reagents employed are rather expensive and their use in the quantity considered renders the process uneconomical when applied to industrial scale production.
The instant invention provides a novel solution to this problem and proposes an electrochemical process which obviates the drawbacks of the prior known process.